The present invention relates to an abnormal sheet delivery detection device which detects that a sheet conveyed by a convey means is delivered to a position other than a normal position.
In order to align the edges of the delivered sheets in a stacked state, a sheet delivery apparatus generally adjusts the position of a sheet release cam, adjusts an air blowing amount for dropping the sheet onto a pile device, and adjusts the air suction amount of a suction wheel which decreases a sheet convey speed by sucking the conveyed sheet. If these adjustment processes are not sufficiently performed, abnormal sheet delivery occurs, e.g., a sheet released from a delivery gripper overrides a lay, or the trailing edge of the sheet remains on the suction wheel. Such abnormal sheet delivery leads to an increase in the amount of wasted paper, and the trouble of a machine when continuing abnormal sheet delivery in this state. In order to prevent these troubles, the sheet delivery apparatus includes the abnormal sheet delivery detection device.
As disclosed in Japanese Utility Model Publication No. 06-11785, a conventional abnormal sheet delivery detection device includes a lay against which the leading edge of the sheet released from the delivery gripper abuts, a pile board on which the sheets whose edges are aligned by the lay are piled, a paper guide arranged above the pile board, a reflection plate arranged above the paper guide, and a reflection-type photoelectric switch which applies light to the reflection plate to detect the sheet conveyed on the paper guide and abnormally delivered.
Since the reflection-type photoelectric switch is arranged upstream of the lay in a sheet convey direction, the above-described conventional abnormal sheet delivery detection device can be applied to only a sheet-fed printing press in which the delivered sheets are piled on one pile board. That is, a printing press with a plurality of (the first and second) pile boards arranged from upstream to downstream in the sheet convey direction cannot identify whether a sheet passing above the first pile board is a sheet to be stacked on the second pile board, or an abnormally delivered sheet to be piled on the first pile board. To solve such problem, the abnormal sheet delivery detection device shown in FIG. 8 has been proposed.
Referring to FIG. 8, a pair of sprockets 103 are rotatably supported at the upper rear ends of a pair of delivery frames 102 arranged to oppose each other at a predetermined gap. A pair of delivery chains 105 which travel in the direction of an arrow A are looped between the sprockets 103 and a pair of sprockets 104 arranged to be coaxial with a delivery cylinder which is in contact with the last printing cylinder. Between the pair of delivery chains 105, a gripper bar having a plurality of delivery grippers 106 which grip and convey a sheet 112 serving as a paper sheet is supported at a predetermined gap in the traveling direction of the delivery chain 105. Note that one of the pair of delivery frames 102, one of the pair of sprockets 103, one of the pair of sprockets 104, and one of the pair of delivery chains 105 are shown in FIG. 8, and the other of each member is not illustrated.
A second pile 108 is arranged downstream of a first pile 107 positioned upstream in the sheet convey direction. A movable sheet release cam 110 is arranged above the first pile 107. When the sheet release cam electromagnetic valve (not shown) is turned on, the rod (not shown) of an air cylinder moves forward to position the movable sheet release cam 110 at an operation position. That is, the movable sheet release cam 110 enters the traveling route of the delivery gripper 106 such that the cam surface of the movable sheet release cam 110 is set as indicated by an alternate long and two short dashed line in FIG. 8. When the cam follower of a gripper shaft which supports the delivery gripper 106 is kept in contact with the cam surface of the entered movable sheet release cam 110, the sheet 112 gripped by the delivery gripper 106 is released and dropped onto the first pile 107.
The first state means a state wherein the movable sheet release cam 110 positions at the operation position, i.e., a state wherein the sheet 112 released from the delivery gripper 106 is dropped onto the first pile 107. On the other hand, when the sheet release cam electromagnetic valve is turned off, the rod (not shown) of the air cylinder moves backward to position the movable sheet release cam 110 at a retreat position. That is, the movable sheet release cam 110 is retreated from the traveling route of the delivery gripper 106 such that the movable sheet release cam 110 is set as indicated by a solid line in FIG. 8. When the movable sheet release cam 110 positions at the retreat position, the sheet 112 gripped by the delivery gripper 106 is not delivered to the first pile 107. The sheet 112 which passes above the first pile 107 is conveyed downstream in the sheet convey direction (the direction of an arrow A), and released above the second pile 108. This state is called the second state. A switching device including the sheet release cam electromagnetic valve and air cylinder switches between the first and second states by moving the movable sheet release cam 110 to the operation/retreat positions.
A stationary sheet release cam 114 is arranged above the second pile 108. The cam surface of the stationary sheet release cam 114 always enters the traveling route of the delivery gripper 106 as shown in FIG. 8. Therefore, in the second state, the cam follower of the gripper shaft which supports the delivery gripper 106 is kept in contact with the cam surface of the stationary sheet release cam 114, and the sheet 112 gripped by the delivery gripper 106 is released and dropped onto the second pile 108.
Suction wheels 116 and 117 are arranged upstream in the sheet convey direction above the first and second piles 107 and 108, respectively. The suction wheels 116 and 117 suck, using air, the trailing edge of the sheet 112 released from the delivery gripper 106 to decrease the convey speed of the sheet 112. Lays 118 and 119 are arranged downstream in the sheet convey direction above the first and second piles 107 and 108, respectively. When the leading edge of the sheet 112 which is released from the delivery gripper 106 and whose convey speed is decreased by the suction wheels 116 and 117 abuts against the lays 118 and 119, the circumferential positions of the sheets 112 which are dropped and piled on the first and second piles 107 and 108 are aligned.
Many fans 120 directed to the first pile 107 are arranged above the first pile 107, and many fans 121 directed to the second pile 108 are arranged above the second pile 108. Since the first and second fans 120 and 121 blow air to the sheet 112 released from the delivery gripper 106, the sheet 112 is dropped and piled on the first pile 107 or second pile 108.
A fan shield 122 can be in contact with or separate from the air intake ports of the fans, of the first fans 120, which blow air to the sheet 112 to be dropped onto the first pile 107, i.e., the fans arranged above the first pile 107 on which the sheet 112 is piled between the suction wheel 116 and the lay 118. When the rod (not shown) of the air cylinder moves forward by turning on the fan shield electromagnetic valve, the fan shield 122 is in contact with the air intake ports of the fans 120 to close them. With this operation, the first fans 120 stop blowing air to the sheet 112 which is gripped by the delivery gripper 106 and passing above the first pile 107. On the other hand, when the rod (not shown) of the air cylinder moves backward by turning off the fan shield electromagnetic valve, the fan shield 122 separates from the air intake ports of the first fans 120 to open them.
The upper end of a detection switch 150 is swingably supported by a bracket (not shown) to which the first fans 120 are attached. The detection switch 150 is arranged downstream of the lay 118 in the sheet convey direction to detect the presence/absence of the sheet 112. The lower end of the detection switch 150 is arranged at a position not to interfere with the gripper bar of the delivery gripper 106.
In this arrangement, the first state is set when the movable sheet release cam 110 enters the traveling route of the delivery gripper 106. Next, the air intake ports of the first fans 120, which have been closed by the fan shield 122, are opened so that the first fans 120 blow air to the sheet 112 above the first pile 107. In this state, as shown in FIG. 8, since the cam follower of the delivery gripper 106 which grips and conveys the sheet 112 is kept in contact with the cam surface of the movable sheet release cam 110, and the sheet 112 is released from the delivery gripper 106. As a result, the released sheet 112 is dropped onto the first pile 107 by air from the first fans 120. In this case, the sheet 112 which has failed to be dropped on the first pile 107, overrides the lay 118, and stays between the first and second piles 107 and 108 is detected by the detection switch 150, thus stopping the operation of the machine.
On the other hand, the second state is set when the movable sheet release cam 110 is retreated from the traveling route of the delivery gripper 106. Next, the air intake ports of the first fans 120 are closed by the fan shield 122 so that the first fans 120 do not blow air to the sheet 112 which is passing above the first pile 107. In this state, since the cam follower of the delivery gripper 106 which grips and conveys the sheet 112 is not kept in contact with the cam surface of the movable sheet release cam 110, the sheet 112 gripped by the delivery gripper 106 passes above the first pile 107 and is conveyed to the second pile 108. Since the lower end of the detection switch 150 is arranged at a position not to interfere with the gripper bar of the delivery gripper 106, the delivery gripper 106 passes below the detection switch 150 without contact with the detection switch 150. When the delivery gripper 106 is kept in contact with the cam surface of the stationary sheet release cam, the sheet 112 conveyed above the second pile 108 is released from the delivery gripper 106, dropped onto the second pile 108, and piled there.
However, in the conventional abnormal sheet delivery detection device, the detection switch 150 is arranged at a high position not to interfere with the gripper bar of the delivery gripper 106. Accordingly, the detection switch 150 is spaced apart above the delivery chain 105. In this arrangement, the sheet which has overridden the lay 118 is not detected by the detection switch 150 until the sheet overrides the gripper bar and jammed. Hence, the detection switch 150 delays detecting the sheet which has overridden the lay 118 or suction wheel, and cannot always detect abnormal sheet delivery reliably and instantaneously, thus posing a problem.